"The president's goal is to have 35 billion gallons of biofuels by 2017, and we're currently at 6 billion gallons. That would mean a huge increase in land for corn," says Jerry Schnoor, a University of Iowa professor of civil and environmental engineering. "The environmental constraints are just too great. It's too much nutrients, too much soil loss, too much pesticides. We don't have the land."
Ethanol advocates vow that the next generation of technology will make ethanol more attractive environmentally. Cellulosic ethanol could be made from cornstalks or, better yet, from perennial crops such as switchgrass. But that's the future. Today, corn, and specifically corn kernels -- little nuggets of starch -- are the sole source of commercial ethanol.